Temperature is one part, albeit a large part, weather conditions are another major factor. If you are lucky enough to get 2 or 3 nice, warmer, stable days in a row, bass will put on the feed bags even in water that is in the lower 40's. Some of my best outings have come in February, after ice out, following a couple of warmer than average days. The trick is knowing where to find them. Look for shallow mud or rock flats close to deeper water and or channel cut banks on the north side of the lake at the end of a warmer day. The angle of the sun will warm these areas faster. Fish the flat right next to the drop off, bass don't like to stray too far from deeper water. Often times you will find bass stacked up in a very small area just because it is a degree or two warmer than the rest of the lake. Start out with search bats like a square bill, chatter bait or super spot. SLOW roll/bounce them off of the bottom, pausing when you hit structure. If you get a steady south wind pushing warmer water on top of them, hold onto your rod:) If they are not actively chasing, try using a tx rigged craw, tube, or a jig. Try shaking and dragging, the key is slow. My last resort is a weigtless 6" slug go (twitch 2-4 times, let sink/die and pause for several seconds, repeat). If I can't catch one on that then I go home.
I guess the point I'm trying to make in all of this is that the magic number can be as low as 42 degrees if the conditions are right. Bass feed throughout the year, even under the ice, they just don't need to feed as often in colder water and will become more selective on what times they do choose to feed. Therefore we need to be more selective on what days we fish early in the year in order to maximize our success.
